HEIDENHAIN TNC 426, User Manual

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36 4 Programming: Fundamentals of NC, File Management, Programming Aids, Pallet Management
4.1 F
undamentals
Polar coordinates
If the production drawing is dimensioned in Cartesian coordinates, you
also write the part program using Cartesian coordinates. For parts
containing circular arcs or angles it is often simpler to give the
dimensions in polar coordinates.
While the Cartesian coordinates X, Y and Z are three-dimensional and
can describe points in space, polar coordinates are two-dimensional
and describe points in a plane. Polar coordinates have their datum at a
circle center (CC), or pole. A position in a plane can be clearly defined
by the:
n
Polar Radius, the distance from the circle center CC to the position,
and the
n
Polar Angle, the size of the angle between the reference axis and
the line that connects the circle center CC with the position.
See figure at upper right.
Definition of pole and angle reference axis
The pole is set by entering two Cartesian coordinates in one of the
three planes. These coordinates also set the reference axis for the
polar angle PA.
Coordinates of the pole (plane) Reference axis of the angle
X/Y +X
Y/Z +Y
Z/X +Z
X
Y
0°
30
10
CC
PR
PA
1
PA
2
PR
PR
PA
3
X
Z
Y
X
Z
Y
X
Z
Y